1/72 scratch build Short S39 Triple Twin

Evening All,

I am making this as part of a GB on another site while I try to finish the Short-Wright biplane. I do not normally take on two projects at the same time, but personal circumstances have prevented me from completing the Short-Wright by the time that the GB started. Hopefully I will not become confused as to what to do next on each project and I will be able to complete both before the deadline for the GB.

I started by making the engines from plastic rod:

Flying surfaces are easy to make and quickly result in something to show for the effort. The wings, tail surfaces, and rudders were made from 30 thou card with the leading and trailing edges sanded and filed to make them into aerofoil sections:

The above shows the front elevator, wings, horizontal tail surface and rudders. The notches in the wings are where the booms will be fixed later.

I have also started to make the propellors from wood - one has been carved, the fuel tanks - there were 42 fixed originally, later two more were added which were of a different shape, and the bench seat for the pilot and passenger. The fuel tanks were shaped from sprue and the seat from 40 thou scrap plastic sheet:

Now I have to make the moulds for the fuselage nacelle.

Thanks for looking.

Stevef.



 

Evening All,

I made the front and rear booms from brass bar as the originals were from square section timber:

Quick and simple to solder. I will prime them later.

I made the fuselage nacelle by push moulding 30 thou plastic sheet which had been heated under a gas grill. I used a scrap of basswood for the male mould and plywood for the female. Unfortunately I made the sides a little too short so I had to trim them and add some card to lengthen the rear: a small piece of card was then glued to the rear to make the back of the nacelle. A strip of scrap plastic was added for the seat and a wheel for the pilot. I know nothing else about the interior and as so little will be visible I left it blank. The joints were filled and sanded and a cowling made from 20 thou card. The card was run between the blade of a pair of scissors and my thumb to make it curl, and then mounted on some stretched sprue formers glued to the front of the nacelle. When all of this was dry I added more filler and sanded it smooth. I forgot to take photos of these processes but the result can be seen below. Holes were drilled in the wings to take the struts and undercarriage later. When all the fuselage assembly was dry I epoxied one of the rear booms to the lower wing and supported it with a sophisticated jig while the epoxy cured:

I used a slightly more complex jig to attach the rear booms to the upper wing:

I now need to make the struts from plastic strip and carve the propellors from wood, following which I will paint as much as I can.

Thanks for looking.

Stevef.

Evening All,

I have painted all, (or almost all), of the parts ready for assembly. The fabric parts were coated with umpteeen, (I lost count!), layers of thinned acrylics - Revell white with Revell Beige 314. The struts were Revell semi-matt enamel (382), and the propellors are carved from wood strip. I also used Humbrol brass enamel for the fuel and oil tanks:

The parts were laid out in the above image to show roughly the order from front, (on the left), to rear (right).

Initial assembly of a pusher is important to get right - everything must be lined up accurately or the model will look odd later. Most pusher types had vertical interplane struts which makes alignment straightforward: a simple jig to keep the leading or trailing edges of the wings in line, and another support to keep the wing tips aligned is all that is required. Paint pots or thick books provide the material for the jigs. I did not photograph them for this build because I forgot to, but if you look up any f my previous builds you will see clearly what I mean.

Setting up a simple structure that is robust enough to be handled but simple to assemble is also straightforward: I cement the outer interplane struts to the lower wing and try to get them as well aligned as possible. When the cement is partially set so that the struts can be moved without falling out, I put small drops of glue into the locating holes of the upper wing and gently lower the upper wing on to the struts. The boom at the rear has to be supported with a paint pot or other suitable jig, (a piece of wood, corner of a book), while the wings are aligned and squared with paint pots as described above. The middle strut of the boom rear was inserted first on this model - it was plastic strip and was glued to the brass booms with CA. Once the CA had set the corner struts at the boom rear were easily inserted and fixed with CA. This kept the rear for the structure rigid while the cement on the interplane struts set:

When this sub-assembly has had 24 hours to set, the remaining struts can be carefully inserted between the wings and booms as the structure is surprisingly rigid.

Thanks for looking.

Stevef.

Evening All,

Having allowed the outer interplane and end boom struts to set overnight, I proceeded to insert the remaining boom stuts with CA as the struts themselves are shaped plastic strip and the booms brass bar. I also added the control horns to the fuselage sides. The inner interplane struts were fitted and allowed to set. These struts were rigged fore-aft with rolled copper wire. One pair of fuel tanks had horizontal struts cemented to the sides and when all of the above was set I was able to add the fuel tanks to the inner interplane struts:

The pair of interplane struts inboard of the outer pair were inserted between the wings before I fitted the final interplane pair: this was because the rear struts of the inner pair are longer than the others - they pass through the wing and will form part of the undercarriage. Using this method of fixing longer struts will hopefully create a stronger undercarriage. The second pair of fuel tanks were fitted with horizontal struts and attached to the interplane struts. Once again I had rigged the fore-aft wires of the inner interplane struts with rolled copper wire before I fixed the fuel tanks in position. While I was adding the interplane struts I also added small pieces of stretched sprue between each strut pair to represent the re-inforcing ribs which were exposed on the underside of the upper wing:

Thanks for looking.

Stevef.

Evening All,

I have been rigging recently using my preferred method with rolled copper wire and CA. It all works fine when the CA works quickly, but it can be a trial when it does not. Fortunately it seems to be working well at the moment. I have added the struts under the upper wing overhang and then rigged them, followed by the fore-aft and rear interplane struts. These are the least accessible and I usually rig these first on my models, following the principle that if the least accessible is rigged first, the task becomes progressively easier. It also means that damage is less likely:

I have also started to put in the supports and drive shafts for the forward propellors. These were made from 30 thou rod and painted black because that seems to have been the colour looking at photos, but I could be wrong. Note that the drive shafts were directly attached to existing struts because this was a modification to an earlier design:

Thanks for looking.

Stevef.

Evening All,

 have fitted the undercarriage, but forgot to take photos of the stages. Briefly the skid and struts are 20 x 30 strip which has been bent to shape (skids) and filed to aerofoil section (legs). The wheels are Eduard PE centres and the tyres 30 thou rod wound around a paintbrush handle and then immersed in very hot water to make a coil. The vertical struts were attached to a skid and the struts inserted into holes on the underside of the wings. The bracing struts were attached and the sub-assembly set aside to dry out, before I repeated the procedure on the other side The axle is brass rod and was CA'd to the skids and the wheels added last. The units were rigged with rolled copper wire.

The rear engine was cemented to the rear of the fuselage nacelles and the propellor glued in place with CA as this will be difficult to reach when the booms have been rigged. I attached the chain drives from the front engine to the prop shafts using thread which I wound around a pin which I had previously glued in the front of the nose. The chains exited via the holes in the fuselage sides seen in earlier pictures. The stabilizing rods were made from plastic rod. The engine was cemented to the pin and the front of the cowling opening added:

The booms have been rigged and the horizontal tail surface CA'd to the top of the rear of the booms. I also added the front booms and elevator:

Thanks for looking.

Stevef.

Evening All,

The rudders were CA'd to the rudder posts at the rear and then the model was inverted so that the tail skids could be put into place. They were made from plastic strip for the skids, and rod for the supports. They were a fiddle and they are not particularly strong, but they are in place.

I had made a set of control horns from 10 x 20 thou strip: there are lots of them and these were put in the respective positions and control cables added from rolled copper wire. The remainder of the rigging was also carried out with rolled copper wire, including the rudder control wires and the anti-drag wires for the front and rear booms. Finally I could add the propellors to the drive shafts in the wings and the model is finished:

As model aircraft look better on a small base I took one from another model just so I could take another photo:

Stevef.